The inventive concept relates to wireless communication, and more particularly, to an apparatus for type-A demodulation, which prevents distortion caused by the distance from a transmitter to a receiver and the communication speed in type-A communication, and an integrated circuit (IC) card including the same.
Radio frequency identification (RFID) is a core technology that is ubiquitous in today's society. RFID is used in various fields, such as national defense, medical care, distribution systems, transportation systems, security systems, manufacturing systems and administration systems. An RFID system including a tag, a reader, and an antenna is a wireless, automatic identification system which receives information from a tag attached to an object or a product using the reader and transmits the information to a network. RFID uses different frequency band in various applications. For example, 125 kHz passive RFID is used for access control, security systems, and animal management; 13.56 MHz passive RFID is used for transport cards, warehousing operations, and distribution of goods; 433 MHz RFID is used for container monitoring and tire pressures sensors; and 900 MHz passive RFID is used for logistics. Of these frequencies, 13.56 MHz passive RFID, also referred to as type-A mode, is most widely used. In the type-A mode, a radio frequency (RF) signal is transferred with modified Miller coding from a transmitter to a receiver or from a reader to a tag or card. An apparatus used in the type-A mode is a type-A demodulator. The type-A demodulator detects a pause in the transmission of the RF signal.
Conventional type-A demodulators may fail if the pause section changes or goes undetected as a result of the distance between a transmitter and a receiver or a reader and a tag or card. Changes in the external environment may also cause type-A demodulators to malfunction.